Field of the Invention
The present invention relates to a liquid ejection head and a liquid ejection apparatus capable of ejecting a liquid such as ink from an ejection opening.
Description of the Related Art
In an inkjet technology that prints an image by ejecting a liquid such as ink, there has been an increasing demand for a high-accuracy and high-quality printing operation in accordance with various application fields of an inkjet printing operation in recent years. In order to improve the accuracy of the printing operation, there is known a method of improving a printing resolution by densely arranging a plurality of ejection openings. Further, in order to realize a high-quality printing operation, there is a need to suppress ink from being thickened due to an evaporation of moisture in an ejection opening in that the thick ink causes a decrease in ejection speed of a liquid droplet or a modulation in color concentration.
As a method of suppressing the ink from being thickened by the evaporation of moisture in the ejection opening, there is known a method in which ink inside a pressure chamber having an ejection opening disposed therein is caused to flow forcedly so that the thick ink staying inside the pressure chamber flows to the outside. However, when a circulation flow amount of the ink flowing in each pressure chamber becomes uneven or a pressure in each pressure chamber becomes uneven, a problem arises in that a difference in ejection characteristic or color concentration between the ejection openings increases. In order to handle this problem, Japanese Patent Laid-Open No. 2009-179049 discloses a method in which a passage resistance of a pressure chamber is kept at 1/100 or less of a passage resistance of a passage supplying ink to the pressure chamber and a passage resistance of a passage collecting ink from the pressure chamber.
However, when the number of the ejection openings constituting an ejection opening row is increased or a gap between the ejection opening rows is narrowed in order to densely arrange the plurality of ejection openings, a problem in Japanese Patent Laid-Open No. 2009-179049 is found. That is, it is found that a change in circulation flow amount of the ink flowing in each pressure chamber or a change in pressure of each pressure chamber is not easily suppressed. When the number of the ejection openings constituting the ejection opening row increases, a distribution of the ejection openings in the row direction of the ejection opening row (the row extension direction) is widened. For that reason, a change in circulation flow amount of the ink flowing in each pressure chamber or a change in pressure of each pressure chamber easily occurs between the plurality of pressure chambers arranged in the row direction of the ejection opening row. Further, when the plurality of ejection opening rows are arranged with high density, it is difficult to increase the width of the passage extending in the row direction of the ejection opening row (the length in the arrangement direction of the plurality of ejection opening rows) due to a relation between the adjacent passages. For that reason, greater pressure loss is generated. As a result, there is a case in which a change in circulation flow amount of the ink flowing in each pressure chamber or a change in pressure of each pressure chamber occurs between the plurality of pressure chambers arranged in the row direction of the ejection opening row.